Field of the Invention
Embodiments of the invention relate to the field of liquid crystal display technology, and specifically, to a curved liquid crystal display panel and a curved liquid crystal display device.
Description of the Related Art
In the In Plane Switching (IPS) mode of a flat liquid crystal display panel, liquid crystal molecules of the penal have an approximate parallel and uniform orientation relative to a surface of a substrate in a non-driven state, so that the oscillation direction of light almost does not change as it passes through the liquid crystal layer. If the polarization directions of two polarizing plates disposed on outer surfaces of two substrates are perpendicular with each other, the liquid crystal display panel will perform a display that is almost entirely black.
In liquid crystal display panel, conventionally, the glasses of the color filter substrate and the array substrate are glasses having positive stress-optical coefficients. For a curved liquid crystal display panel of the In Plane Switching (IPS) mode, surface of the curved liquid crystal display panel for display is usually concave. Thus, a surface of the color filter substrate of the flat liquid crystal display panel of the IPS mode facing the users should be curved inward, such that the glass of the color filter substrate is subject to compression, and the glass of the array substrate is subjected to stretching. Through testing, it is found that the main optical axis of the curved glass of the color filter substrate and the main optical axis of the curved glass of the array substrate are perpendicular with each other, the angle between the main optical axis of the curved glass of the color filter substrate and the initial orientation of the curved liquid crystal layer is variable and a maximum value of the variable angle is 45 degree, wherein the initial orientation of the curved liquid crystal layer is an orientation of the liquid crystal layer in a non-driven state before the liquid crystal layer is curved. The following description is based on the following situation, in which the angle between the main optical axis of the curved glass of the color filter substrate and the initial orientation of the curved liquid crystal layer is the maximum angle of 45 degree. As shown in FIG. 1, the arrows in the upper polarizing plate 31 and the lower polarizing plate 32 indicate respective polarization direction of the plates, the arrows in the glass 11 of the color filter substrate and the glass 12 of the array substrate indicate respective main optical axis direction of the glasses, and the arrow in the liquid crystal layer 20 indicates an initial orientation of the curved liquid crystal layer. An angle between the polarization direction of the lower polarizing plate 32 and the initial orientation of the curved liquid crystal layer 20 is 0 degree, an angle between the main optical axis direction of the glass 12 of array substrate and the initial orientation of the curved liquid crystal layer 20 is 135 degrees, an angle between the main optical axis direction of the glass 11 of color filter substrate and the initial orientation of the curved liquid crystal layer 20 is 45 degrees, an angle between the polarization direction of the upper polarizing plate 31 and the initial orientation of the curved liquid crystal layer 20 is 90 degrees. Natural light emitted by a backlight source firstly passes through the lower polarizing plate 32 and becomes linearly polarized light; the linearly polarized light passes through the glass 12 of the array substrate subjected to stretching and having a positive stress-optical coefficient and becomes elliptically polarized light due to the optical rotation effect of the glass 12 of the array substrate; at this time, the liquid crystal layer may also rotate light because the light enters the liquid crystal layer is no longer the linearly polarized light in parallel or perpendicular with the orientation of the liquid crystals; after being rotated by the curved liquid crystal layer, light enters the glass 11 of the color filter substrate being subjected to compression and is affected by the optical rotation effect of the glass of the color filter substrate 11. As shown in FIG. 2, the arrow pointing upwards indicates the optical rotation effect of the glass of the array substrate, the circular arc having an arrow indicates the optical rotation effect of the curved liquid crystal layer, and the arrow pointing downwards indicates the optical rotation effect of the glass of the color filter substrate. It can be seen that, the light having been rotated for three times is diverged far from the original light. The same principle applies when the angel between the main optical axis of the curved glass of the color filter substrate and the initial orientation of the liquid crystal layer is an angle having a different degree. In such a way, before light enters the upper polarizing plates, there may be various oscillation directions of light, such that a certain part of light may pass through the upper polarizing plate, causing a significant light leak of the curved liquid crystal display panel of the IPS mode.